The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Internal combustion engines, particularly those configurations utilized in passenger car and light truck applications, have been the subject of extensive and exhaustive development effort. One of the more recent results of such effort involves the operation of an internal combustion engine as a flexible fuel engine, i.e., an engine operating on a variety of fuels, most commonly gasoline and E85 (a mixture of 85 percent ethanol (grain alcohol) and 15 percent gasoline). While a flexible fuel engine presently offers certain advantages from the standpoints of fuel expense and the larger issue of foreign oil dependency, there are operational issues which are the subject of significant contemporary research and development.
For example, spark ignition internal combustion engines operating on ethanol or E85 have better knock tolerance when operating under wide open throttle or full load conditions than the same engine operating on gasoline. Because by its very nature the flexible fuel engine must operate on a variety of fuels, its operation on ethanol is very often compromised. Improving the performance and efficiency of a flexible fuel engine operating on ethanol is thus an important goal and the goal to which this invention is directed.